Semiconductor device and manufacturing method thereof

ABSTRACT

A semiconductor device includes a Fin FET device. The Fin FET device includes a first fin structure extending in a first direction and protruding from an isolation insulating layer, a first gate stack including a first gate electrode layer and a first gate dielectric layer, covering a portion of the first fin structure and extending in a second direction perpendicular to the first direction, and a first source and a first drain, each including a first stressor layer disposed over the first fin structure. The first fin structure and the isolation insulating layer are disposed over a substrate. A height Ha of an interface between the first fin structure and the first stressor layer measured from the substrate is greater than a height Hb of a lowest height of the isolation insulating layer measured from the substrate.

RELATED APPLICATIONS

This application is a Continuation Application of U.S. Ser. No.16/056,148 filed Aug. 6, 2018, which is a Continuation Application ofU.S. Ser. No. 15/402,398 filed Jan. 10, 2017, now U.S. Pat. No.10,043,906, which is a Divisional Application of U.S. Ser. No.14/749,597 filed Jun. 24, 2015, now U.S. Pat. No. 9,564,528, whichclaims priority of U.S. Provisional Application No. 62/104,066 filed onJan. 15, 2015, the entire contents of each of which is incorporatedherein by reference.

TECHNICAL FIELD

The disclosure relates to a semiconductor integrated circuit, moreparticularly to a semiconductor device having a fin structure and itsmanufacturing process.

BACKGROUND

As the semiconductor industry has progressed into nanometer technologyprocess nodes in pursuit of higher device density, higher performance,and lower costs, challenges from both fabrication and design issues haveresulted in the development of three-dimensional designs, such as a finfield effect transistor (Fin FET). Fin FET devices typically includesemiconductor fins with high aspect ratios and in which channel andsource/drain regions of semiconductor transistor devices are formed. Agate is formed over and along the sides of the fin structure (e.g.,wrapping) utilizing the advantage of the increased surface area of thechannel and source/drain regions to produce faster, more reliable andbetter-controlled semiconductor transistor devices. In some devices,strained materials in source/drain (S/D) portions of the FinFETutilizing, for example, silicon germanium (SiGe), silicon phosphide(SiP) or silicon carbide (SiC), may be used to enhance carrier mobility.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detaileddescription when read with the accompanying figures. It is emphasizedthat, in accordance with the standard practice in the industry, variousfeatures are not drawn to scale and are used for illustration purposesonly. In fact, the dimensions of the various features may be arbitrarilyincreased or reduced for clarity of discussion.

FIG. 1A is an exemplary process flow chart for manufacturing asemiconductor FET device having a fin structure (Fin FET);

FIGS. 1B and 1C are exemplary perspective views of the Fin FET deviceaccording to one embodiment of the present disclosure; and

FIGS. 2-16 show exemplary processes for manufacturing the Fin FET deviceaccording to one embodiment of the present disclosure.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides manydifferent embodiments, or examples, for implementing different featuresof the invention. Specific embodiments or examples of components andarrangements are described below to simplify the present disclosure.These are, of course, merely examples and are not intended to belimiting. For example, dimensions of elements are not limited to thedisclosed range or values, but may depend upon process conditions and/ordesired properties of the device. Moreover, the formation of a firstfeature over or on a second feature in the description that follows mayinclude embodiments in which the first and second features are formed indirect contact, and may also include embodiments in which additionalfeatures may be formed interposing the first and second features, suchthat the first and second features may not be in direct contact. Variousfeatures may be arbitrarily drawn in different scales for simplicity andclarity.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly. In addition, the term“made of” may mean either “comprising” or “consisting of.”

FIG. 1A is an exemplary flow chart for manufacturing a semiconductor FETdevice having a fin structure (Fin FET). FIGS. 1B and 1C are exemplaryperspective views of the Fin FET device according to one embodiment ofthe present disclosure. As shown in FIGS. 1B and 1C, fin structures 20protruding from an isolation insulating layer 50 are disposed over asubstrate 10 and a gate structure 110 is formed over the fin structures.In FIG. 1B, a Fin FET device 1 includes plural fin structures, while inFIG. 1C, a Fin FET device 2 includes one fin structure.

The flow chart of FIG. 1A illustrates only a relevant part of the entiremanufacturing process for a Fin FET device. It is understood thatadditional operations may be provided before, during, and afterprocesses shown by FIG. 1A, and some of the operations described belowcan be replaced or eliminated, for additional embodiments of the method.The order of the operations/processes may be interchangeable. Further,the general operations for manufacturing a recessed S/D structure withstrain materials (or stressor) in the fin structure are disclosed inU.S. Pat. No. 8,440,517, the entire contents of which are incorporatedherein by reference.

In S1001, a fin structure is fabricated over a substrate. In S1002, agate structure including a gate dielectric layer and a gate electrode isformed over a portion of the fin structure. In S1003, a region for asecond type of FET, for example, a p-type FET, is covered by a coveringlayer to protect the region for the second type of FET from thesubsequent processes for a first type of FET, for example an n-type FET.In S1004, the fin structure not covered by the gate structure isrecessed. In S1005, a stressor layer is formed in the recessed portionof the fin structure. After forming the stressor structure for the firsttype of FET, in S1006, a region for the first type of FET is covered bya cover layer to protect the first type of FET with the stressorstructure from the subsequent processes for the second type of FET. InS1007, the fin structure not covered by the gate structure for thesecond type of FET is recessed. In S1008, a stressor layer is formed inthe recessed portion of the fin structure for the second type of FET. Itis possible to process a p-type FET first and then process an n-typeFET.

Referring to FIGS. 2-15B, the details of the exemplary manufacturingprocess of a Fin FET are described.

FIG. 2 is an exemplary cross sectional view of the Fin FET device 1having a substrate 10 at one of the various stages of the fabricationprocess according to one embodiment.

To fabricate a fin structure, a mask layer is formed over the substrate10 by, for example, a thermal oxidation process and/or a chemical vapordeposition (CVD) process. The substrate 10 is, for example, a p-typesilicon substrate with an impurity concentration being in a range ofabout 1.12×10¹⁵ cm⁻³ and about 1.68×10¹⁵ cm⁻³. In other embodiments, Thesubstrate 10 is an n-type silicon substrate with an impurityconcentration being in a range of about 0.905×10¹⁵ cm⁻³ and about2.34×10¹⁵ cm⁻³. The mask layer includes, for example, a pad oxide (e.g.,silicon oxide) layer and a silicon nitride mask layer in someembodiments.

Alternatively, the substrate 10 may comprise another elementarysemiconductor, such as germanium; a compound semiconductor includingIV-IV compound semiconductors such as SiC and SiGe, III-V compoundsemiconductors such as GaAs, GaP, GaN, InP, InAs, InSb, GaAsP, AlGaN,AlInAs, AlGaAs, GaInAs, GaInP, and/or GaInAsP; or combinations thereof.In one embodiment, the substrate 10 is a silicon layer of an SOI(silicon-on insulator) substrate. When an SOI substrate is used, the finstructure may protrude from the silicon layer of the SOI substrate ormay protrude from the insulator layer of the SOI substrate. In thelatter case, the silicon layer of the SOI substrate is used to form thefin structure. Amorphous substrates, such as amorphous Si or amorphousSiC, or insulating material, such as silicon oxide may also be used asthe substrate 10. The substrate 10 may include various regions that havebeen suitably doped with impurities (e.g., p-type or n-typeconductivity).

The pad oxide layer may be formed by using thermal oxidation or a CVDprocess. The silicon nitride mask layer may be formed by a physicalvapor deposition (PVD), such as a sputtering method, a CVD,plasma-enhanced chemical vapor deposition (PECVD), an atmosphericpressure chemical vapor deposition (APCVD), a low-pressure CVD (LPCVD),a high density plasma CVD (HDPCVD), an atomic layer deposition (ALD),and/or other processes.

The thickness of the pad oxide layer is in a range of about 2 nm toabout 15 nm and the thickness of the silicon nitride mask layer is in arange of about 2 nm to about 50 nm in some embodiments. A mask patternis further formed over the mask layer. The mask pattern is, for example,a resist pattern formed by lithography operations.

By using the mask pattern as an etching mask, a hard mask pattern 100 ofthe pad oxide layer 101 and the silicon nitride mask layer 102 isformed. The width of the hard mask pattern 100 is in a range of about 5nm to about 40 nm in some embodiments. In certain embodiments, the widthof the hard mask patterns 100 is in a range of about 7 nm to about 12nm.

As shown in FIG. 2, by using the hard mask pattern 100 as an etchingmask, the substrate 10 is patterned into fin structures 20 by trenchetching using a dry etching method and/or a wet etching method. A heightH1 (in the Z direction) of the fin structure 20 is in a range of about100 nm to about 300 nm. In certain embodiments, the height is in a rangeof about 50 nm to about 100 nm. When the heights of the fin structuresare not uniform, the height from the substrate may be measured from theplane that corresponds to the average heights of the fin structures.

In this embodiment, a bulk silicon wafer is used as a starting materialand constitutes the substrate 10. However, in some embodiments, othertypes of substrate may be used as the substrate 10. For example, asilicon-on-insulator (SOI) wafer may be used as a starting material, andthe insulator layer of the SOI wafer constitutes the substrate 10 andthe silicon layer of the SOI wafer is used for the fin structures 20.

As shown in FIG. 2, two fin structures 20 are disposed adjacent to eachother in the Y direction in a first device region 1A and in a seconddevice region 1B, respectively. However, the number of the finstructures is not limited to two. The numbers may be one, three, four orfive or more. In addition, one of more dummy fin structures may bedisposed adjacent to both sides of the fin structures 20 to improvepattern fidelity in patterning processes. The width W1 of the finstructure 20 is in a range of about 5 nm to about 40 nm in someembodiments, and may be in a range of about 7 nm to about 15 nm incertain embodiments. The height H1 of the fin structure 20 is in a rangeof about 100 nm to about 300 nm in some embodiments, and may be in arange of about 50 nm to 100 nm in other embodiments. The space S betweenthe fin structures 20 is in a range of about 5 nm to about 80 nm in someembodiments, and may be in a range of about 7 nm to 15 nm in otherembodiments. One skilled in the art will realize, however, that thedimensions and values recited throughout the descriptions are merelyexamples, and may be changed to suit different scales of integratedcircuits.

In this embodiment, the first device region 1A is for n-type Fin FETsand the second device region 1B is for p-type Fin FETs.

FIG. 3 is an exemplary cross sectional view of the Fin FET device 1having fin structures 20 at one of the various stages of the fabricationprocess according to one embodiment.

As shown in FIG. 3, an isolation insulating layer 50 is formed over thesubstrate 10 so as to fully cover the fin structure 20.

The isolation insulating layer 50 includes one or more layers ofinsulating materials such as silicon oxide, silicon oxynitride orsilicon nitride, formed by LPCVD (low pressure chemical vapordeposition), plasma-CVD or flowable CVD. In the flowable CVD, flowabledielectric materials instead of silicon oxide are deposited. Flowabledielectric materials, as their name suggest, can “flow” duringdeposition to fill gaps or spaces with a high aspect ratio. Usually,various chemistries are added to silicon-containing precursors to allowthe deposited film to flow. In some embodiments, nitrogen hydride bondsare added. Examples of flowable dielectric precursors, particularlyflowable silicon oxide precursors, include a silicate, a siloxane, amethyl silsesquioxane (MSQ), a hydrogen silsesquioxane (HSQ), anMSQ/HSQ, a perhydrosilazane (TCPS), a perhydro-polysilazane (PSZ), atetraethyl orthosilicate (TEOS), or a silyl-amine, such as trisilylamine(TSA). These flowable silicon oxide materials are formed in amultiple-operation process. After the flowable film is deposited, it iscured and then annealed to remove un-desired element(s) to form siliconoxide. When the un-desired element(s) is removed, the flowable filmdensifies and shrinks. In some embodiments, multiple anneal processesare conducted. The flowable film is cured and annealed more than once.The flowable film may be doped with boron and/or phosphorous. Theisolation insulating layer 50 may be formed by one or more layers ofSOG, SiO, SiON, SiOCN and/or fluoride-doped silicate glass (FSG) in someembodiments.

FIG. 4 is an exemplary cross sectional view of the Fin FET device 1having fin structures 20 at one of the various stages of the fabricationprocess according to one embodiment.

After forming the isolation insulating layer 50, a planarizationoperation is performed so as to remove part of the isolation insulatinglayer 50 and the mask layer 100 (the pad oxide layer 101 and the siliconnitride mask layer 102). Then, the isolation insulating layer 50 isfurther removed so that an upper part of the fin structure 20, which isto become a channel layer, is exposed, as shown in FIG. 4. Theplanarization operation may include a chemical mechanical polishing(CMP) and/or an etch-back process.

In at least one embodiment, the silicon nitride layer 102 may be removedusing a wet process using hot H₃PO₄, while pad oxide layer 101 may beremoved using dilute HF acid, if formed of silicon oxide. In somealternative embodiments, the removal of the mask layer 100 may beperformed after the recessing of the isolation insulating layer 50.

In certain embodiments, the partially removing the isolation insulatinglayer 50 may be performed using a wet etching process, for example, bydipping the substrate in hydrofluoric acid (HF). In another embodiment,the partially removing the isolation insulating layer 50 may beperformed using a dry etching process, for example, the dry etchingprocess using CHF₃ or BF₃ as etching gases.

In some embodiments, the surface 51 of the isolation insulating layer 50may have a shape, in which the isolation regions 50 have raised portionsat the sides of the fin structures, and in other embodiments, thesurface of the isolation insulating layer 50 may be substantially flat.

After forming the isolation insulating layer 50, a thermal process, forexample, an anneal process, may be performed to improve the quality ofthe isolation insulating layer 50. In certain embodiments, the thermalprocess is performed by using rapid thermal annealing (RTA) at atemperature in a range of about 900° C. to about 1050° C. for about 1.5second to about 10 second in inert gas ambient, for example, N₂, Ar orHe ambient.

FIG. 5 is an exemplary cross sectional view of the Fin FET device 1having fin structures 20 at one of the various stages of the fabricationprocess according to one embodiment. FIGS. 6A and 6B are exemplary crosssectional views along the direction (X direction) in which the finstructures extend.

A gate dielectric layer 105 and a poly silicon layer are formed over theisolation insulating layer 50 and the exposed fin structures 20, andthen patterning operations are performed so as to obtain gate stacksincluding gate electrode layers 110A and 110B made of poly silicon andthe gate dielectric layer 105. The patterning of the poly silicon layeris performed by using a hard mask 200 including a silicon nitride layer201 and an oxide layer 202 in some embodiments. In other embodiments,the layer 201 may be silicon oxide and the layer 202 may be siliconnitride. The gate dielectric layer 105 may be silicon oxide formed byCVD, PVD, ALD, e-beam evaporation, or other suitable process. In someembodiments, the gate dielectric layer 105 may include one or morelayers of silicon oxide, silicon nitride, silicon oxy-nitride, or high-kdielectric materials. High-k dielectric materials comprise metal oxides.Examples of metal oxides used for high-k dielectrics include oxides ofLi, Be, Mg, Ca, Sr, Sc, Y, Zr, Hf, Al, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb,Dy, Ho, Er, Tm, Yb, Lu, and/or mixtures thereof. In some embodiments, athickness of the gate dielectric layer is in the range of about 1 nm to5 nm. In some embodiments, the gate dielectric layer 105 may include aninterfacial layer made of silicon dioxide.

In some embodiments, the gate electrode layers 110A and 110B maycomprise a single layer or multilayer structure. In the presentembodiment, the gate electrode layers 110A and 110B may comprisepoly-silicon. Further, the gate electrode layers 110A and 110B may bedoped poly-silicon with uniform or non-uniform doping. In somealternative embodiments, the gate electrode layers 110A and 110B mayinclude a metal such as Al, Cu, W, Ti, Ta, TiN, TiAl, TiAlN, TaN, NiSi,CoSi, other conductive materials with a work function compatible withthe substrate material, or combinations thereof. The gate electrodelayers 110A and 110B may be formed using a suitable process such as ALD,CVD, PVD, plating, or combinations thereof.

The width W2 of the gate electrode layers 110A and 110B is in the rangeof about 30 nm to about 60 nm in some embodiments.

Further, side-wall insulating layers 80 are also formed at both sides ofthe gate electrode layers 110A and 110B. The side-wall insulating layers80 may include one or more layers of silicon oxide, silicon nitride,silicon oxy-nitride, or other suitable material. The side-wallinsulating layers 80 may comprise a single layer or multilayerstructure. A blanket layer of a side-wall insulating material may beformed by CVD, PVD, ALD, or other suitable technique. Then, ananisotropic etching is performed on the side-wall insulating material toform a pair of side-wall insulating layers (spacers) 80 on opposingsides of the gate stack. The thickness of the side-wall insulatinglayers 80 is in a range of about 5 nm to about 15 nm in someembodiments. In certain embodiments, the side-wall insulating layers 80may not be formed at this stage.

FIGS. 7A and 7B are exemplary cross sectional views and FIG. 7C is anexemplary perspective view of the Fin FET device 1 having gatestructures over fin structures at one of the various stages of thefabrication process according to one embodiment.

As shown in FIGS. 7A-7C, a cover layer 120 is formed over the gatestructures and the fin structures in the first and second deviceregions. The cover layer 120 may include silicon nitride with athickness in a range of about 5 nm to about 15 nm in some embodiments.

FIGS. 8A and 8B are exemplary cross sectional views and FIG. 8C is anexemplary perspective view of the Fin FET device 1 having gatestructures over fin structures at one of the various stages of thefabrication process according to one embodiment.

As shown in FIGS. 8A-8C, a masking layer 130 is formed over the coveringlayer 120, and further a mask pattern 135 is formed over the maskinglayer 130 by using a lithographic process. The mask pattern 135 coversthe second device region 1B as shown in FIGS. 8B and 8C. The maskinglayer 130 may include an organic material. In some embodiments, themasking layer includes a material used for a bottom anti-reflectioncoating (BARC) for a lithographic process. The mask pattern 135 mayinclude a photo resist.

FIG. 9A is an exemplary perspective view and FIG. 9B is an exemplarycross sectional view along X1-X1 in FIG. 9A of the Fin FET device 1having gate structures over fin structures at one of the various stagesof the fabrication process according to one embodiment. In FIG. 9B, fourfin structures 20A in the first device region 1A are illustrated forexplanatory purposes, while FIG. 9A illustrates two fin structures 20Ain the first device region 1A, but the number of the fin structures isnot limited to four or two.

By using the mask pattern 135, the masking layer 130 is etched, and byusing the etched masking layer, the cover layer (SiN) 120 in the firstdevice region is anisotropically etched. As shown in FIGS. 9A and 9B,the cover layer 120 in the first device region 1A is removed except forside portions of the fin structures 20A and side portions of the gatestack. The upper surfaces of the fin structures 20A are exposed. In someembodiments, part of the side portions of the cover layer 120 is alsoetched.

In some embodiments, a single layer of photoresist is formed over thesecond device region 1B, and by using the photo resist layer as a mask,the cover layer 120 is etched. After the cover layer 120 is etched, themasking layer 130 (and the mask pattern 135, if it remains) is removed.In some embodiments, the surface 51A of the isolation insulating layer50 may have a shape, in which the isolation regions 50 have raisedportions at the sides of the fin structures, and in other embodiments,the surface of the isolation insulating layer 50 may be substantiallyflat.

In some embodiments, the etching of cover layer 120 is performed byusing CH₃F, CH₂F₂, CF₄, Ar, HBr, N₂, He and/or O₂ as etching gas under apressure of 3˜50 mTorr at a temperature of 20 to 70° C.

FIG. 10A is an exemplary perspective view, FIG. 10B is an exemplarycross sectional view along X1-X1 of FIG. 10A, and FIGS. 10C-10E areexemplary cross sectional views of the Fin FET device 1 having finstructures at one of the various stages of the fabrication processaccording to one embodiment. FIGS. 10D and 10E are enlarged views of thecircled portion of FIG. 10C.

The portions of the fin structure 20A not covered by the gate structureare recessed to form a recessed portion 140A of the fin structure 20A.The recessed portion 140A is formed such that a top surface of the finstructure 20A is located below the top surface of the isolationinsulating layer 50.

In certain embodiments, a biased etching process is performed to recessthe top surface of the fin structure 20A that are unprotected or exposedto form the recessed portion 140A. During the recess etching, orsubsequently, the cover layers 120 located adjacent to the finstructures are removed.

As shown in FIGS. 10B-10E, part of the upper surface 51A of theisolation insulating layer 50 between the fin structures is alsorecessed, and both the upper surface 51A of the isolation insulatinglayer 50 and the upper surfaces 21A of the recessed fin structures 20Ahave a concave shape (a smiling shape). For example, a smiling shape canbe found at the region of the isolation insulation layer 50 between thecenter fin structure 20A-11 and the left fin structure 20A-2 and/or atthe region of the isolation insulation layer 50 between the center finstructure 20A-1 and the right fin structure 20A-3.

In FIG. 10D, a depth D1 of the upper surface 21A of the recessed finstructure 20A (20A-1) measured from the upper-most surface 52A of theisolation insulating layer 50 around the fin structures is greater thana depth D2 of the upper surface 51A of the recessed portion of theisolation insulating layer 50 between the fin structures measured fromthe upper-most surface 52A of the isolation insulating layer 50, i.e.,D1>D2. D1 is in a range of about 0 nm to about 100 nm, and D2 is also ina range about 0 nm to about 100 nm in some embodiments.

In FIG. 10E, the depth D1 of the upper surface 21A of the recessed finstructure 20A (20A-1) measured from the upper-most surface 52A of theisolation insulating layer 50 around the fin structures is smaller thanthe depth D2 of the upper surface 51A of the recessed portion of theisolation insulating layer 50 between the fin structures measured fromthe upper-most surface 52A of the isolation insulating layer 50, i.e.,0≤D1≤D2 (but D1 and D2 are not zero at the same time). In someembodiments, 0<D1<D2. D1 is in a range of about 0 nm to about 100 nm,and D2 is also in a range about 0 nm to about 100 nm in someembodiments. The difference ΔD between D1 and D2 is in a range of about10 nm to 70 nm, in some embodiments, and in a range of about 20 nm to 50nm in other embodiments. The depth D2 may be measured at either theregion of the isolation insulation layer 50 between the center finstructure 20A-1 and the left fin structure 20A-2 and/or at the region ofthe isolation insulation layer 50 between the center fin structure 20A-1and the right fin structure 20A-3.

In some embodiments, the recess etching is performed by using Ar, HBr,N₂ and/or He as etching gas under a pressure of 3˜50 mTorr at atemperature of 20 to 70° C.

FIG. 11A is an exemplary cross sectional view and FIG. 11B is anexemplary perspective view of the Fin FET device 1 having gatestructures over fin structures at one of the various stages of thefabrication process according to one embodiment.

In the recessed portion 140A, a first stressor layer 300 is formed. Thefirst stressor layer 300 may be formed by selectively growing a strainedmaterial over the recessed portion 140A and above the isolationinsulating layer 50. Since the lattice constant of the strained materialis different from the fin structure 20 and the substrate 10, the channelregion of the fin structure 20 is strained or stressed to increasecarrier mobility of the device and enhance the device performance.

In one embodiment of the present disclosure, the first stressor layer300 is SiC, SiP and/or SiCP for an n-type Fin FET. As shown in FIG. 10E,when the depth D1 and the depth D2 satisfy D1≤D2, a volume ofepitaxially grown stressor layer 300 becomes greater than the case whereD1>D2. Further, when D1≤D2 is satisfied, a position of the stressorlayer 300 can be more accurately controlled, and a gate resistanceand/or a source/drain resistance can be reduced.

In at least one embodiment, SiC as the stressor layer 300 can beepitaxially-grown by an LPCVD process to form the source and drainregions of the n-type FinFET. The LPCVD process is performed at atemperature of about 400 to 800° C. and under a pressure of about 1 to200 Torr, using Si₃H₈ and SiH₃CH as reaction gases, in some embodiments.

In the present embodiment, the selective growth of the first stressorlayer 300 continues until the material 300 extends vertically a distanceranging from about 10 to 100 nm from the bottom of the recessed portion140A and extends laterally over the top surfaces of the isolationinsulating layer 50. The formed first stressor layer 300 corresponds tosource/drain of the n-type Fin FET. The first stressor layer 300 may bea single layer or may include multiple stressor layers.

Further, in some embodiments, a cap layer 310 may be additionally formedover the stressor layer 300. The cap layer 310 enhances an applicationof the stress by the stressor layer 300 to the channel layer. In otherembodiments, a protective layer made of, for example, silicon nitride,may be formed over the stressor layer.

After the Fin FETs in the first device region 1A (e.g., n-type Fin FETs)are formed, the Fin FETs in the second device region 1B are processed ina similar matter to the first device region.

FIGS. 12A and 12B are exemplary cross sectional views and FIG. 12C is anexemplary perspective view of the Fin FET device 1 having fin structures20 at one of the various stages of the fabrication process according toone embodiment.

Similar to FIGS. 7A and 7B, a cover layer 140 is formed over the gatestructures and the fin structures in the first and second deviceregions. The cover layer 140 may include silicon nitride with athickness in a range of about 5 nm to about 15 nm in some embodiments.

Similar to FIGS. 8A-8C, a masking layer 150 is formed over the coveringlayer 140, and further a mask pattern 155 is formed over the maskinglayer 150 by using a lithographic process. The mask pattern 155 coversthe first device region 1A as shown in FIGS. 12A and 12C. The maskinglayer 150 may include an organic material. In some embodiments, themasking layer 150 includes a material used for a bottom anti-reflectioncoating (BARC) for a lithographic process. The mask pattern 155 mayinclude a photo resist.

Similar to FIGS. 9A and 9B, by using the mask pattern 155, the maskinglayer 150 is etched, and by using the etched masking layer 150, thecover layers 120 and 140 in the second device region are anisotropicallyetched. Similar to FIGS. 9A and 9B, the cover layers in the seconddevice region 1B are removed except for side portions of the finstructures 20B and side portions of the gate stack. The upper surfacesof the fin structures 20B are exposed. The cover layers (SiN) 120 and140 in the second device region 1B are removed, while the cover layer140 still covers the first device region 1A to protect the first deviceregion from the subsequent operation for the second device region. Insome embodiments, a single layer of photo resist is formed over thefirst device region 1A, and by using the photo resist layer, the coverlayers 120 and 140 in the second device region are etched. After thecover layer 120 and 140 are etched, the masking layer 150 (and the maskpattern 155, if it remains) is removed. It is noted that similar to FIG.4, the surface 51B of the isolation regions 50B has a smiling profile.

FIG. 13A is an exemplary perspective view, FIG. 13B is an exemplarycross sectional view along Y1-Y1 of FIG. 13A, and FIGS. 13C-13E areexemplary cross sectional views of the Fin FET device 1 having finstructures at one of the various stages of the fabrication processaccording to one embodiment. FIGS. 13D and 13E are enlarged views of thecircled portion of FIG. 10C. In FIG. 13B, four fin structures 20B in thesecond device region 1B are illustrated, while FIG. 13A illustrates twofin structures 20B in the second device region 1B, but the number of thefin structures is not limited to four or two.

The portions of the fin structure 20B not covered by the gate structureare recessed to form a recessed portion 140B of the fin structure 20B.The recessed portion 140B is formed such that a top surface of the finstructure 20B is located below the top surface of the isolationinsulating layer 50.

In certain embodiments, using the cover layers 120 and 140 remaining onthe side walls of the fin structure 20B as hard masks, a biased etchingprocess is performed to recess the top surface of the fin structure 20Bthat are unprotected or exposed to form the recessed portion 140B.Subsequently, the cover layers 120 and 140 located adjacent to the finstructures are removed.

As shown in FIGS. 13B-13E, the upper surface 51B of the isolationinsulating layer 50 between the fin structures is also recessed, andboth the upper surface 51B of the isolation insulating layer 50 and theupper surfaces 21B of the recessed fin structures 20B have a concaveshape (a smiling shape).

In FIG. 13D, a depth D1′ of the upper surface 21B of the recessed finstructure 20B measured from the upper-most surface 52B of the isolationinsulating layer 50 around the fin structures is greater than a depthD2′ of the upper surface 51B of the recessed portion of the isolationinsulating layer 50 between the fin structures measured from theupper-most surface 52B of the isolation insulating layer 50, i.e.,D1′>D2′. D1′ is in a range of about 0 nm to about 100 nm, and D2′ isalso in a range about 0 nm to about 100 nm in some embodiments.

In FIG. 13E, the depth D1′ of the upper surface 21B of the recessed finstructure measured from the upper-most surface 52B of the isolationinsulating layer 50 around the fin structures is smaller than the depthD2′ of the upper surface 51B of the recessed portion of the isolationinsulating layer 50 between the fin structures measured from theupper-most surface 52B of the isolation insulating layer 50, i.e.,0≤D1′≤D2′ (but D1′ and D2′ are not zero at the same time). In someembodiments, 0<D1′<D2′. D1′ is in a range of about 0 nm to about 100 nm,and D2′ is also in a range about 0 nm to about 100 nm in someembodiments. The difference ΔD′ between D1′ and D2′ is in a range ofabout 10 nm to 70 nm, in some embodiments, and in a range of about 20 nmto 50 nm in other embodiments.

FIG. 14A is an exemplary cross sectional view and FIG. 14B is anexemplary perspective view of the Fin FET device 1 having gatestructures over fin structures at one of the various stages of thefabrication process according to one embodiment.

In the recessed portion 140B, a second stressor layer 305 is formed. Thesecond stressor layer 305 may be formed by selectively growing astrained material over the recessed portion 140B and above the isolationinsulating layer 50. Since the lattice constant of the strained materialis different from the fin structure 20B and the substrate 10, thechannel region of the fin structure 20B is strained or stressed toincrease carrier mobility of the device and enhance the deviceperformance.

In one embodiment of the present disclosure, the second stressor layer305 is SiGe for a p-type Fin FET. As shown in FIG. 13E, when the depthD1′ and the depth D2′ satisfy D1′≤D2′, a volume of epitaxially grownstressor layer 305 becomes greater than the case where D1′>D2′. Further,when D1′≤D2′ is satisfied, a position of the second stressor layer 305can be more accurately controlled, and a gate resistance and/or asource/drain resistance can be reduced.

In at least one embodiment, SiGe as the second stressor layer 305 can beepitaxially-grown by an LPCVD process to form the source and drainregions of the p-type FinFET. The LPCVD process is performed at atemperature of about 400 to 800° C. and under a pressure of about 1 to200 Torr, using SiH₄ and GeH₄ as reaction gases, in some embodiments.

In the present embodiment, the selective growth of the second stressorlayer 305 continues until the material 305 extends vertically a distanceranging from about 10 to 100 nm from the bottom of the recessed portion140B and extends laterally over the top surfaces of the isolationinsulating layer 50. The formed second stressor layer 305 corresponds tothe source/drain of the p-type Fin FET. The second stressor layer 305may be a single layer or may include multiple stressor layers.

Further, in some embodiments, a cap layer 315 is formed over thestressor layer 305. When the stressor layer 305 is SiGe, the cap layer315 is Si epitaxially-grown by an LPCVD process. The cap layer 315enhances application of the stress by the stressor layer 305 to thechannel layer.

FIGS. 15A and 15B are exemplary cross sectional views of the Fin FETdevice 1 having fin structures 20 at one of the various stages of thefabrication process according to one embodiment. FIG. 15A is anexemplary cross sectional view along X1-X1 of FIG. 14B and FIG. 15B isan exemplary cross sectional view along Y1-Y1 of FIG. 14B. In FIGS. 15Aand 15B, four fin structures 20A and 20B are illustrated for anexplanation purpose, while FIG. 14B illustrates two fin structures 20Aand 20B in the first and second device regions, respectively, but thenumber of the fin structures is not limited to four or two.

As shown in FIG. 15A, an interlayer dielectric layer 400 is formed overthe gate structures and the sources/drains in the first device region1A. The dielectric layer 400 is also formed over the gate structures andthe sources/drains in the second device region 1B, as shown in FIG. 15B.

As shown in FIG. 15A, a height H2 of the interface between the finstructure 20A and the first stressor layer 300 is greater than a heightH3 of the isolation insulating layer 50 (the lowest height between thefins structures), measured from the substrate. The difference ΔH betweenH2 and H3 is in a range of about 10 nm to 70 nm, in some embodiments,and in a range of about 20 nm to 50 nm in other embodiments.

Similarly, as shown in FIG. 15B, a height H2′ of the interface betweenthe fin structure 20B and the second stressor layer 305 is greater thana height H3′ of the isolation insulating layer 50 (the lowest heightoutside the fin structure area, or the lowest height between the finsstructures), measured from the substrate. The difference ΔH′ between H2′and H3′ is in a range of about 10 nm to 70 nm, in some embodiments, andin a range of about 20 nm to 50 nm in other embodiments.

Although the first and second stressor layers 300 and 305 and the caplayers 310 and 315 are separately formed in FIGS. 15A and 15B, theadjacent cap layers 310 and/or 315 may be connected in certainembodiments.

It is understood that the Fin FETs in the first and second deviceregions may undergo further CMOS processes to form various features suchas contacts/vias, interconnect metal layers, dielectric layers,passivation layers, etc. The modified insulation and strained structureprovides a given amount of strain into channel region of a FinFET,thereby enhancing the device performance.

FIG. 16 shows an exemplary cross section view of a Fin FET device 2having a fin structure 20C (see, FIG. 1C) at one of the various stagesof the fabrication process according to another embodiment of thepresent disclosure.

In the Fin FET device 1, plural fin structures are disposed with apredetermined interval. On the other hand, in the Fin FET device 2, onestructure is disposed over the substrate as an isolated Fin FET. It isnoted that the term “isolated” means that a distance to another Fin FETis more than 5×W1′ (W1′ is a width of the upper part of the finstructure just below the surface of the isolation insulating layer).

As shown in FIG. 16, the Fin FET device 2 includes a fin structure 20C,a stressor layer 301, a cap layer 306, an isolation insulating layer 50and an interlayer dielectric layer 400. Fin FET device 2 may be ann-type Fin FET or a p-type Fin FET. When the fin FET device 2 is ann-type Fin FET, the stressor layer 301 may be SiC, SiP and/or SiCP. Whenthe fin FET device 2 is a p-type Fin FET, the stressor layer 301 may beSiGe. The stressor layer 301 may be a single layer or may includemultiple stressor layers.

As shown in FIG. 16, a height H2″ of the interface between the finstructure 20C and the stressor layer 301 is greater than a height H3″ ofthe isolation insulating layer 50, measured from the substrate. Theheight H3″ is measured at a position of a distance L from the center ofthe fin structure 20C. The distance L is in a range about 2.5×W1 toabout 5×W1. The difference ΔH″ between H2″ and H3″ is in a range ofabout 10 nm to 70 nm, in some embodiments, and in a range of about 20 nmto 50 nm in other embodiments.

Similar to the fabrication processes of the Fin FET device 1 shown inFIGS. 10E and/or 13E, in forming a recess of the fin structure 20C, adepth of the upper surface of the recessed fin structure 20C is setsmaller than a depth of the upper surface of the recessed portion of theisolation insulating layer. Accordingly, a volume of epitaxially grownstressor layer 301 can be greater, a position of the stressor layer 301can be more accurately controlled, and a gate resistance and/or asource/drain resistance can be reduced.

It is understood that the Fin FET device 2 may undergo further CMOSprocesses to form various features such as contacts/vias, interconnectmetal layers, dielectric layers, passivation layers, etc. The modifiedinsulation and strained structure provides a given amount of strain intochannel region of a Fin FET, thereby enhancing the device performance.

The various embodiments or examples described herein offer severaladvantages over the existing art. In the present disclosure, a depth(height) of the isolation insulating layer (STI oxide) and a depth(height) of the fin recess in the source/drain regions are controlled,thereby controlling dimensions of an epitaxial layer formed in the finrecess in the FinFET process. For example, a depth of the upper surfaceof the recessed fin structure measured from the upper-most surface ofthe isolation insulating layer around the fin structures is set smallerthan a depth of the upper surface of the recessed portion of theisolation insulating layer between the fin structures measured from theupper-most surface of the isolation insulating layer. By doing so, avolume of epitaxially grown stressor layer can be greater, a position ofthe stressor layer can be more accurately controlled, and a gateresistance and/or a source/drain resistance can be reduced. Accordingly,it is possible to improve device performance (e.g., gain, speed andstability).

It will be understood that not all advantages have been necessarilydiscussed herein, no particular advantage is required for allembodiments or examples, and other embodiments or examples may offerdifferent advantages.

In accordance with one aspect of the present disclosure, a method formanufacturing a semiconductor device includes forming a fin structureover a substrate. An isolation insulating layer is formed so that anupper part of the fin structure protrudes from the isolation insulatinglayer. A gate structure is formed over a part of the fin structure andover the isolation insulating layer. Recesses are formed in theisolation insulating layer at both sides of the fin structure. A recessis formed in a portion of the fin structure which is not covered by thegate structure. The recess in the fin structure and the recesses in theisolation insulating layer are formed such that a depth D1 of the recessin the fin structure and a depth D2 of the recesses in the isolationinsulating layer measured from an uppermost surface of the isolationinsulating layer satisfy 0≤D1≤D2 (but D1 and D2 are not zero at the sametime).

In accordance with another aspect of the present disclosure, a methodfor manufacturing a semiconductor device includes forming fin structuresover a substrate. The fin structures include a center fin structure, aleft fin structure and a right fin structure. An isolation insulatinglayer is formed so that upper parts of the fin structures protrude fromthe isolation insulating layer. A gate structure is formed over a partof the fin structures and over the isolation insulating layer. Recessesare formed in the isolation insulating layer at least at a portionbetween the left fin structure and the center fin structure and aportion between the right fin structure and the center fin structure.Recesses are formed in portions of the left, center and right finstructures, which are not covered by the gate structure. The recesses inthe left, center and right fin structures and the recesses in theisolation insulating layer are formed such that a depth D1 of the recessin the center fin structure and a depth D2 of at least one of therecesses in the isolation insulating layer formed between the left finstructure and the center fin structure and between the right finstructure and the center fin structure satisfy 0≤D1≤D2 (but D1 and D2are not zero at the same time), where D1 and D2 are measured from anuppermost surface of the isolation insulating layer located between theleft fin structure and the center fin structure or between the right finstructure and the center fin structure.

In accordance with another aspect of the present disclosure, asemiconductor device includes a Fin FET device. The Fin FET deviceincludes a first fin structure extending in a first direction andprotruding from an isolation insulating layer, the first fin structureand the isolation insulating layer being disposed over a substrate. TheFin FET device also includes a first gate stack including a first gateelectrode layer and a first gate dielectric layer, covering a portion ofthe first fin structure and extending in a second directionperpendicular to the first direction. The Fin FET device furtherincludes a first source and a first drain, each including a firststressor layer disposed over the first fin structure. The first stressorlayer applies a stress to a channel layer of the first fin structureunder the first gate stack. A height Ha of an interface between thefirst fin structure and the first stressor layer measured from thesubstrate is greater than a height Hb of a lowest height of theisolation insulating layer measured from the substrate.

The foregoing outlines features of several embodiments or examples sothat those skilled in the art may better understand the aspects of thepresent disclosure. Those skilled in the art should appreciate that theymay readily use the present disclosure as a basis for designing ormodifying other processes and structures for carrying out the samepurposes and/or achieving the same advantages of the embodiments orexamples introduced herein. Those skilled in the art should also realizethat such equivalent constructions do not depart from the spirit andscope of the present disclosure, and that they may make various changes,substitutions, and alterations herein without departing from the spiritand scope of the present disclosure.

What is claimed is:
 1. A semiconductor device, comprising: a Fin FETdevice including: a first fin structure disposed over a substrate andextending in a first direction; an isolation insulating layer disposedover the substrate; a gate electrode disposed over the first finstructure and extending in a second direction crossing the firstdirection; and a first source/drain stressor layer made of semiconductormaterial and disposed over the first fin structure, wherein: the firstsource/drain stressor layer is in contact with the isolation insulatinglayer and the first fin structure, and in a cross section along thesecond direction, a bottom of the first source/drain stressor layer incontact with the isolation insulating layer and the first fin structurehas a rounded convex shape toward the first fin structure.
 2. Thesemiconductor device of claim 1, wherein: the Fin FET device furtherincludes: a second fin structure disposed adjacent to the first finstructure; and a second source/drain stressor layer disposed over thesecond fin structure, and a surface of the isolation insulating layerbetween the first fin structure and the second fin structure has arounded convex shape toward the substrate.
 3. The semiconductor deviceof claim 2, wherein a bottom of the rounded convex shape of the firstsource/drain stressor layer is located above a bottom of the roundedconvex shape of the isolation insulating layer.
 4. The semiconductordevice of claim 2, wherein a bottom of the rounded convex shape of thefirst source/drain stressor layer is located below a bottom of therounded convex shape of the isolation insulating layer.
 5. Thesemiconductor device of claim 2, wherein a bottom of the rounded convexshape of the first source/drain stressor layer is located at a samelevel as a bottom of the rounded convex shape of the isolationinsulating layer.
 6. The semiconductor device of claim 1, wherein thefirst source/drain stressor layer includes at least one of SiP, SiC andSiCP.
 7. The semiconductor device of claim 1, wherein the firstsource/drain stressor layer includes SiGe.
 8. A semiconductor device,comprising: a Fin FET device including: a first fin structure disposedover a substrate and extending in a first direction; an isolationinsulating layer disposed over the substrate; a gate electrode disposedover the first fin structure and extending in a second directioncrossing the first direction; a first source/drain stressor layer madeof semiconductor material and disposed over the first fin structure; andan interlayer dielectric layer, wherein: the first source/drain stressorlayer is in contact with the isolation insulating layer and the firstfin structure, and in a cross section along the second direction, abottom of the first source/drain stressor layer in contact with thefirst fin structure has a rounded convex shape toward the first finstructure.
 9. The semiconductor device of claim 8, wherein: the Fin FETdevice further includes: a second fin structure disposed adjacent to thefirst fin structure; and a second source/drain stressor layer disposedover the second fin structure, and a surface of the isolation insulatinglayer between the first fin structure and the second fin structure has arounded convex shape toward the substrate.
 10. The semiconductor deviceof claim 9, wherein a lowest portion of the bottom of the firstsource/drain stressor layer is located between a lowest portion of therounded convex shape of the isolation insulating layer and an highestportion of the isolation insulating layer.
 11. The semiconductor deviceof claim 9, wherein a lowest portion of the rounded convex shape of theisolation insulating layer is located between a lowest portion of thebottom of the first source/drain stressor layer and an highest portionof the isolation insulating layer.
 12. The semiconductor device of claim9, wherein a different between a lowest portion of the rounded convexshape of the isolation insulating layer and a lowest portion of thebottom of the first source/drain stressor is in a range from 10 nm to 70nm.
 13. The semiconductor device of claim 8, wherein the firstsource/drain stressor layer includes at least one of SiP, SiC and SiCP.14. The semiconductor device of claim 8, wherein the first source/drainstressor layer includes SiGe.
 15. A semiconductor device, comprising: anisolation insulating layer disposed over a substrate; a first finstructure disposed over the substrate and extending in a firstdirection; a second fin structure disposed over the substrate; a gateelectrode disposed over the first fin structure and extending in asecond direction crossing the first direction: a first source/drainstressor layer disposed over the first fin structure and made of adifferent material than the first fin structure; and a secondsource/drain stressor layer disposed over the second fin structure andmade of a same material as the first stressor layer, wherein: in a crosssection along the second direction, a bottom of the first source/drainstressor layer in contact with the first fin structure has a roundedconvex shape toward the first fin structure, and in a cross sectionalong the second direction, a bottom of the second source/drain stressorlayer in contact with the second fin structure has a rounded convexshape toward the first fin structure.
 16. The semiconductor device ofclaim 15, wherein an upper surface of the isolation insulating layerbetween the first fin structure and the second fin structure has arounded convex shape toward the substrate.
 17. The semiconductor deviceof claim 16, wherein the first and second source/drain stressor layersare in contact with the isolation insulating layer.
 18. Thesemiconductor device of claim 16, wherein a lowest portion of therounded convex shape of the first and second source/drain stressorlayers is located below a lowest portion of the rounded convex shape ofthe isolation insulating layer.
 19. The semiconductor device of claim15, wherein the first and second source/drain stressor layers include atleast one of SiP, SiC and SiCP.
 20. The semiconductor device of claim15, wherein the first and second source/drain stressor layers includesSiGe.